This invention relates to a method of laying cables which allows the cable to be rewound downstream of an obstacle onto a second reel and which allows the cable to be laid into the ground without twist.
U.S. Pat. No. 4,890,957 of the present inventor issued Jan. 2, 1990 discloses a method which was a first attempt to provide a technique for the laying of cable such as fiber optic cables in which the cable is unwound from the first supply reel at an obstacle such as a rail bed and rewound onto a second reel downstream of the reel for continuation of the laying process using the second reel as the supply downstream of the obstacle.
This patent discloses particularly in FIGS. 9 through 12 an arrangement in which the cable is taken off from the supply reel with the inner end being pulled from the reel over one end after removal of one end flange and collapsing of the hub of the reel. The inner end is then drawn through an opening excavated at the obstacle and rewound onto the second reel.
At a second obstacle the technique shows the second reel being collapsed similarly to the first reel and the cable unwound from the inner end outwardly. The above patent discloses an arrangement in which each of the reels has only one end flange which is removable so that the other end flange is fixed. The patent states that the problem of ensuring the cable is laid without twist is solved by the arrangements as shown. To the contrary, however, this technique has unfortunately been found to be ineffective and instead exacerbates the problem of the twist. This occurs because, if the second reel is collapsed and the cable withdrawn therefrom at the second obstacle in a manner which is symmetrical to that of the first reel at the first obstacle then the twist, instead of being cancelled is indeed summated so that the cable wound again onto the first reel carries a severe twist which cannot be accommodated in the cable when laid.
Unfortunately therefore the first arrangement as disclosed in the above patent has been found to be unsatisfactory but this failure has only been determined after careful analysis of the matter and careful review of the techniques involved.